JP3335215B2 - Absorbent articles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to absorbent articles, and more particularly to disposable articles represented by sanitary napkins, disposable diapers and the like, and complicated articles such as viscous and solid contents. TECHNICAL FIELD The present invention relates to an absorbent article having excellent liquid absorbency having various properties.

[0002]

2. Description of the Related Art In general, absorbent articles represented by sanitary napkins, disposable diapers and the like are made of a hydrophobic non-woven fabric such as a polyolefin-based nonwoven fabric for quickly transferring a liquid to an absorbent layer and suppressing discomfort to the skin. A surface sheet that has been subjected to hydrophilic treatment, etc., and an absorbent layer made of a combination of a sheet-like material such as cotton or tissue such as wood pulp and a polymer absorber to absorb and retain the liquid, And a liquid-proof sheet made of a polyethylene film or the like disposed on the back surface of the absorption layer for preventing leakage of the water to the outside.
In such an absorbent article, (1) the liquid permeates promptly and does not cause lateral leakage, and (2) the liquid absorbed by the absorbent layer does not return to the surface again (hereinafter, referred to as “wetting resistance resistance”). Is the most required performance. It is also an important required performance to minimize the feeling of stuffiness and foreign objects at the time of wearing and to have an excellent wearing feeling.

Conventionally, various studies have been made to satisfy such performance. For example, Japanese Patent Application Laid-Open No. Sho 62-12506
No. 1 discloses that a perforated nonwoven sheet is used as a surface sheet to improve the absorbability of menstrual blood and the like, and Japanese Patent Application Laid-Open No. 62-181041 discloses a liquid permeable nonwoven sheet. To improve the permeability of liquids, especially highly viscous liquids, by having an average fiber-to-fiber distance. But,
Liquids such as menstrual blood and highly viscous liquids that are viscous or contain solids are difficult to be absorbed by the absorbent layer, so even if the topsheet has excellent permeability, the absorption rate of the absorbent layer cannot keep up, There was a limit to the improvement in absorbency. In addition, Japanese Unexamined Patent Application Publication No.
Japanese Patent Application Laid-Open No. 89053 discloses that a diffusion sheet made of a hydrophilic fiber is provided between a topsheet and an absorbent layer to suppress liquid return to the surface and lateral leakage of the liquid. However, since this diffusion sheet is made of hydrophilic fiber, the fiber itself is absorbed when diffusing the liquid, and when a body pressure or the like is applied, the diffusion sheet may seep out to the top sheet and return to wet.

[0004] Thus, the side leakage of the absorbent article is suppressed,
Improvements have been made to the absorbent layer including the topsheet and the diffusion sheet in order to improve the absorbability and the resistance to re-wetting, but at present, satisfactory products have not been obtained.
Regarding the improvement of the feeling of wearing, attempts have been made to improve the feeling of stuffiness by using a moisture-permeable film for the liquid-proof sheet, such as sanitary napkins and disposable diapers on the market, but there is a limit due to the wetting back to the surface . In addition, in sanitary napkins, the sanitary napkins themselves have been made thinner to reduce the foreign body sensation during wear. At present, comfortable wearing feeling is not obtained.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems, and to cause a liquid having a complicated property such as a viscous or solid content to cause a lateral leakage. SUMMARY OF THE INVENTION An object of the present invention is to provide an absorbent article that absorbs quickly without discomfort, minimizes discomfort to the skin, and has an excellent wearing feeling such as being soft and having a close feeling.

[0006]

The absorbent article of the present invention comprises:
An absorbent article comprising a liquid-permeable top sheet, an absorbing layer that absorbs and retains a liquid, and a liquid-impermeable liquid-proof sheet disposed on the back of the absorbing layer, wherein the top sheet and the absorbing layer Fibers to quickly spread the liquid during
A knitted diffusion sheet having a content of 2 to 50% is interposed.

As the diffusion sheet used in the present invention, any knitted sheet produced by a warp knitting machine, a circular knitting machine or a flat knitting machine may be used. In addition, these knitted materials may be obtained by a knitting machine having a single-row needle bed (single) or a double-row needle bed (double). Further, the knitted fabric used for the diffusion sheet is preferably the following knitted fabric in order to quickly diffuse the liquid from the topsheet and transfer the liquid to the absorption layer. The material of the knitted fabric may be any material such as synthetic fiber, natural fiber, and regenerated fiber.However, in order to prevent the absorbed liquid from returning to the surface, at least the side facing the topsheet is required. Preferably, hydrophobic fibers are present. The fineness of the fibers used for the knitted fabric is not particularly limited, but it is preferable to use ultrafine fibers having a low fineness in terms of flexibility, absorbency, diffusibility and the like. The cross-sectional shape of the fiber is not particularly limited, but a deformed cross-section such as silk is preferred from the viewpoint of diffusion transferability. Although the density of the knitted fabric is not particularly limited, the fiber content is set to 2. because the liquid diffusibility is excellent, the diffused liquid is promptly transferred to the absorbent layer, and it is flexible and retains shape retention. The range is 0 to 50.0%. Here, the fiber content is obtained by calculating the ratio of the fiber occupied per unit area by the following formula. Fiber content (%) = [basis weight (g / m ² )
× 10 ⁻⁴ / (thickness (cm) × fiber density (g / cm ³ ))) × 100 Also, the thickness of the knitted fabric is determined from the viewpoint of liquid wettability and wearing feeling.
The value measured at a contact pressure of 100 g / cm ² is 0.1 to 5.
It is preferably 0 mm.

In the present invention, since the above-mentioned knitted sheet is used between the topsheet and the absorbent layer as the diffusion sheet, the liquid permeating through the topsheet can be promptly diffused to promote absorption. In addition, since the absorbent layer does not adhere to the topsheet, wetting of the liquid once absorbed is suppressed, and due to the cushioning characteristic of the knit, flexibility is maintained even with thin napkins, etc., and it is easy to adhere to the body when worn, An absorptive article with excellent wearing feeling is obtained.

The top sheet used in the present invention includes:
It has a function of rapidly sending a liquid to an absorption layer, and is, for example, a polyolefin such as polyethylene or polypropylene, a polyester such as polyethylene terephthalate, a polyamide such as nylon 6, nylon 6,6, an acrylic such as polyacrylonitrile, or rayon. And non-woven fabrics such as cellulose, cotton and the like, or a mixture thereof, and a perforated film. Among these, a nonwoven fabric sheet or a hydrophobic perforated film obtained by subjecting a nonwoven fabric using a hydrophobic fiber to a hydrophilic treatment with a surfactant or the like can not only quickly feed the liquid into the absorbent layer but also suppress the wetting back. Preferred for effect. As the nonwoven fabric sheet, a long-fiber nonwoven fabric sheet manufactured by a spun bond method or the like, a short fiber nonwoven fabric sheet manufactured by a heat bonding method, a thermal bonding method, or the like is used.

The absorbing layer used in the present invention has a function of absorbing and retaining a large amount of liquid and preventing the liquid once absorbed from returning to the surface. Wood pulp,
A cotton-like material such as cellulosic cotton, cotton, rayon fiber, a sheet-like material such as tissue or rayon non-woven fabric, or a combination of these with a polymer absorber is preferably used, but those which further improve the absorbency. However, it is not limited to these. As the waterproof sheet used in the present invention, a polyolefin-based, polyester-based, polyamide-based, acrylic-based film, or the like is used, which has an action of preventing liquid from leaking to the outside. It is preferable to use a moisture-permeable sheet made of a microporous film of polyethylene or the like from the viewpoint of suppressing the stuffiness at the time of wearing.

[0011]

The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the invention thereto. Example 1 A polypropylene spunbond nonwoven fabric sheet having a basis weight of 20 g / m ² and a thickness of 0.2 mm was treated with polyoxyethylene octyl phenyl ether (Toho Chemical Co., Ltd., Triton X-100 (registered trademark)) as a water-permeable agent. After that, a hole having a hole diameter of 1.5 mm and a hole area ratio of 7.2% was formed into a perforated nonwoven fabric and used as a surface sheet. Further, using a 22 g double double circular knitting machine with a false twisted yarn of polyethylene terephthalate 150d / 96f, the thickness is 1.
1 mm, basis weight 240 g / m ² , density 27 courses / inch, 31 wales / inch, fiber content 15.8%
A circular knit knit, which is a knitted fabric having a smooth structure, was prepared and used as a diffusion sheet. Surface sheet and diffusion sheet obtained above, absorbent layer (product made from Kao Corporation, consisting of wood pulp and polyacrylic acid-based polymer absorber, trade name "Lorrier", thickness 3 mm) and liquidproof sheet (A moisture-permeable polyethylene film, thickness 0.3 mm) were laminated in this order to obtain a sanitary napkin.

[Example 2] In Example 1, a short fiber having a cut length of 20 mm consisting of two components, polyethylene and polypropylene, was carded as a surface sheet, and was thermally bonded to a short fiber having a basis weight of 20 g / m and a thickness of 0.2 mm ² . A sanitary napkin was obtained in the same manner as in Example 1 except that a fiber nonwoven fabric was used. [Example 3] In Example 1, a polyethylene film having a thickness of 0.03 mm was used as a surface sheet and a hole diameter of 0.5 m was used.
A sanitary napkin was obtained in the same manner as in Example 1, except that a perforated film having a hole area ratio of 17.6% was used.

Example 4 In Example 1, polyethylene terephthalate 50d / 350 was used as the diffusion sheet.
A half-structure having a thickness of 0.2 mm, a basis weight of 105 g / m ² , a density of 58 courses / inch, a density of 40 wales / inch, and a fiber content of 34.9% was obtained using a 28 gauge single tricot machine using the ultrafine fibers of f. A sanitary napkin was obtained in the same manner as in Example 1 except that a certain tricot knitted fabric was used. [Example 5] A sanitary napkin was obtained in the same manner as in Example 1 except that the short fiber nonwoven fabric used in Example 2 was used as a surface sheet, and the tricot knitted fabric used in Example 4 was used as a diffusion sheet. Example 6 A sanitary napkin was obtained in the same manner as in Example 1, except that the perforated film used in Example 3 was used as a topsheet, and the tricot knitted fabric used in Example 4 was used as a diffusion sheet.

[Comparative Example 1] In Example 1, a rayon short fiber having a cut length of 20 mm was carded as a diffusion sheet and subjected to needle punching to obtain a sheet-like short sheet having a basis weight of 40.0 g / m ² and a thickness of 0.3 mm. A sanitary napkin was obtained in the same manner as in Example 1 except that a fiber nonwoven fabric was used. Comparative Example 2 A sanitary napkin was obtained in the same manner as in Comparative Example 1, except that the short fiber nonwoven fabric used in Example 2 was used as the topsheet. Comparative Example 3 Comparative Example 1 was the same as Comparative Example 1, except that the perforated film used in Example 3 was used as the topsheet.
A sanitary napkin was obtained in the same manner as described above. [Comparative Examples 4, 5, and 6] Sanitary napkins were prepared in the same manner as in Examples 1, 2, and 3 except that the diffusion sheet was not used in Examples 1, 2, and 3, respectively. Obtained.

[Test Examples] Examples 1 to 6 and Comparative Examples 1 to
The liquid sanitary napkins obtained in 6 were evaluated for liquid absorbency, anti-wetting property and wearability by the following methods. The results are shown in Table 1. (1) Liquid absorptivity: The absorption time (seconds) of a certain amount of liquid was measured and compared for the liquid absorptivity. That is, 5 cc of the test liquid is dropped on the surface sheet, and the time until the light on the surface of the test liquid disappears is measured. If the absorption time is 4 seconds or less, the liquid is absorbed before it spreads to the side. It was evaluated that it was excellent in leak prevention and that it flowed before it was absorbed for 10 seconds or more, and that there was a risk of causing lateral leak.

(2) Rewetting resistance: The rate of rewetting after liquid absorption was measured, and the rewetting properties, which are the greatest cause of discomfort, were compared. That is, after dropping 5 cc of the test solution onto the topsheet and pressurizing for 5 minutes to absorb the liquid, place the filter paper on the topsheet and pressurize again for 5 minutes to determine the amount of the test solution that has returned to the filter paper. According to the equation, the wetting return rate of 5% or less was defined as a range in which discomfort was suppressed, and a discomfort was evaluated to be quite uncomfortable at 10% or more. Rewetting rate (%) = (g of test solution wetted on filter paper) / (g of test solution dropped) x 100 (3) Feeling of wearing: The elasticity due to compression was measured to determine the feeling when wearing the absorbent article. Simulated and compared wearing feeling.
That is, the compression work per unit area is measured by a compression tester KES-FB3 (manufactured by Kato Tech Co., Ltd.), and the larger this value is, the more elastic and soft the compression work is, and the compression work is 10 g.
Feel soft when worn with f · cm / cm ² or more, 6gf ·
At cm / cm ² or less, it was evaluated that the substance did not adhere to the body and had a foreign body sensation. The test liquids (1) and (2) used were prepared using menstrual blood as a model. That is, as a result of examining menstrual blood, it was found that it had a viscosity of about 10 cps and contained a small amount of solids such as cell walls.
A small amount of flour was dissolved in the PVA aqueous solution of Example 1 to prepare a test solution.

[0017]

[Table 1]

From Table 1, it can be seen that in Examples 1 to 6, the liquid absorption time was all 4 seconds or less, the liquid absorption was excellent, and the liquid was quickly absorbed without causing lateral leakage. In addition, the short-fiber nonwoven fabric, which has a rewetting rate of 5% or less, is excellent in rewetting resistance, has less discomfort due to the re-wetting of liquid once absorbed, and has a poor rewetting resistance in the past. It can also be seen that the use of a knitted diffusion sheet significantly improves the wet-back resistance. Furthermore, since the compression work amount has reached approximately 10 gf · cm / cm ² , it can be seen that it has an excellent wearing feeling, is flexible and fits the body, and has little foreign body feeling.

[0019]

According to the present invention, by using a knitted diffusion sheet having a specific fiber content between the topsheet and the absorbent layer, it is possible to reduce the viscosity or the solid content. A liquid having complicated properties can be quickly absorbed without causing lateral leakage, the discomfort given to the skin can be minimized, and an absorbent article having an excellent wearing feeling can be obtained. Absorbent articles of the present invention, in addition to sanitary napkins, disposable diapers, etc., surgical allowance materials, breast milk pads, etc., absorbent pads for body fluids, absorbent sheets, etc. It is used for applications such as absorbent pads for special liquids such as oils and various wipers, and can be used in various other fields.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) A61F 13/15-13/84 A61F 5/44

Claims (1)

(57) [Claims] 1. An absorbent article comprising a liquid-permeable top sheet, an absorbing layer that absorbs and retains liquid, and a liquid-impermeable liquid-proof sheet disposed on the back surface of the absorbing layer.
An absorbent article comprising a knitted diffusion sheet having a fiber content of 2 to 50% for rapidly diffusing a liquid between the topsheet and the absorbent layer.